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<pre class="textdiagram" id="fig23">
+----------------+
|                |
|   Publisher    |
|                |
+--------+-------+
|  PUB   |  REP  |
\---+----+-----+-/
    |      ^   |
    |      |   |
    |     (1)  |
   [3]     |   |
    |      |  (2)
    |      |   |
    v      |   v
/--------+-+-----\
|  SUB   |  REQ  |
+--------+-------+
|                |
|   Subscriber   |
|                |
+----------------+
</pre>
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